connect to facebook login error
Please navigate to Dashboard > Comments > Settings > Social Login & Share admin page make sure the "Use Facebook OAuth2" option is enabled. Delete all caches and check again (not on Incognito mod).
We don't find such an issue on our test websites.
This is a configuration issue for sure. Please check the points one more time and make sure you've done all the steps correctly.
Especially you'll need to pay attention to Valid OAuth Redirect URIs fields. The issue comes from the URL you've filled in that filed.